JPS61175045A - Ink jet head - Google Patents

Abstract

PURPOSE:To increase reliability of an ink check-valve by using a ball. CONSTITUTION:A check-valve consisting of a ball 8 and a ball guide 7 is provided within an ink supply entrance 3, and if a pulse voltage is applied to a piezoelectric body 1, the capacity of an ink chamber 5 instantly decreases and uniform pressure is created within the ink chamber, pushing the ball 8 tightly against the ink supply entrance 3, and the back flow of the ink is prevented. And the ink is discharged only from a nozzle 4 where there is no resistance. When the piezoelectric body 1 restored its normal condition, a negative pressure is created within the ink chamber 5, causing the ball 8 to be released from the ink supply entrance 3 and to stop at where the ball guide 7 is provided, and the ink is supplied into the ink chamber 5. The ball guide 7 is fixed to the wall of the ink chamber 5 around the ink supply entrance 3, and is conically shaped with its top cut off and retains the ball 8 to be able to contact with and released from the supply entrance 3 without deviating from the center. Thus, the function of the back flow valve is accurate and its structure is simplified, resulting in production of a reliable product.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a structure for preventing backflow of ink in an ink head of an inkjet printer.

2. Description of the Related Art A conventional inkjet printer head is shown in FIG. In Fig. 4, 1 is an electrostrictive vibrator, 2 is a main body, 3 is an ink supply port, 4 is a nozzle, 5 is an ink chamber, and 6
is a rectifier valve, and the structure in this head is the ink chamber 5.
A pulse voltage is applied to the piezoelectric body (electrostrictive vibrator) 1 forming a part of the ink chamber 5 to reduce the volume of the ink chamber 5 and generate a pressure wave. This is a device that injects particles. At this time, the movement of the rectifier plate 6, which is a rectifier valve, brings the ink supply port 3 into close contact with the ink chamber 5 when the volume of the ink chamber 5 decreases, thereby preventing ink from flowing backward. When the volume of the ink chamber 50 returns to a steady state, the nozzle supply port is moved away and ink is supplied to the ink chamber 5.

Problems to be Solved by the Invention In this conventional structure, the plate serving as the rectifier valve 6 is made as light and small as possible in order to vibrate at a high frequency. Therefore, it has the disadvantage that a minute misalignment of the plate can cause backflow, and since this is also a plate, it has been extremely difficult to align the nozzle with the supply port.

Means for Solving the Problems In order to solve the above problems, a backflow prevention valve using a ball was provided at the ink supply port.

Function According to the present invention, the ball, which is a check valve, comes into close contact with the ink supply port or separates from the ink supply port depending on the pressure in the ink chamber.

Example Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram corresponding to FIG. 1 of one embodiment of the present invention.

In Fig. 1, the same parts as in Fig. 4 are given the same reference numerals, and the explanation thereof will be omitted.The new point is that a check valve is provided, which is constituted by a ball 8 attached to the ink supply port and its ball guide 7. This is what is happening.

The volume of the ink chamber 5 decreases at the moment when a pulse voltage is applied to the piezoelectric body 1, but at that time, the ink presses the ink chamber with the same pressure, and the ball 8 is also pushed toward the ink supply port 3 and comes into close contact with it. Prevent ink from flowing backwards. Then, the ink is ejected only from the nozzle section 4 with no resistance. When the piezoelectric body 1 returns to a steady state, the ink chamber 5 becomes a negative pressure, so the ball 8 moves away from the ink supply port 3 and stops at the ball guide 7 position, and ink is supplied to the ink chamber 5. It will be done.

The diameter of the ball 8 is larger than the diameter of the ink supply port 3. The ball guide 7 is fixed around the ink supply port 3 on the wall surface of the ink chamber 5 having the ink supply port 3, and has a truncated conical shape, has an opening 10 in the center of its tip surface, and has an opening 10 on the circumferential surface of the cone. (a plurality of slits extending in the cone axis direction) 11
．． It has 11... These allow pressure changes in the ink chamber 5 to be quickly and accurately transmitted to the ball 8, and make it easier for ink to flow from the supply port 3 into the chamber 5. Further, since the ball 8 is conical, it has the function of holding the ball 8 so that it can move toward and away from the supply port 3 without being eccentric.

Effects of the Invention According to the present invention, as described above, since a ball is used as an ink backflow prevention valve, the ball can be reliably brought into close contact with the ink supply port without having to center it accurately like a plate. As a result, the function of the check valve is accurate, the structure is simplified, and a highly reliable valve can be provided at a low cost.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the embodiment of the present invention in a steady state;
The figure is a sectional view of the ink jetting state shown in FIG. 1, FIG. 3 is an enlarged perspective view of the check valve shown in FIG. 1, and FIG. 4 is a sectional view of the conventional valve. 1 is a piezoelectric body (electrostrictive vibrator), 2 is an ink head body, 3
is an ink supply port, 4 is a nozzle, 5 is an ink chamber, 6 is a ball guide with a hole, 7 is a ball, and 8 is an ink droplet.

Claims (2)

[Claims] (1) An inkjet head for an inkjet printer, characterized in that a ball is used as an ink backflow prevention valve. (2) The ball is held in a conical guide fixed to the circumferential surface of the ink supply port of the ink chamber so as to be able to approach and separate from the ink supply port, and the tip surface of the conical guide and the conical circumferential surface The inkjet head according to claim 1, wherein the inkjet head is provided with an opening.